Assuming that a roughness meter can be successfully employed to measure the roughness on the internal surface of irrigation pipes, this research had the purpose of defining parameters and procedures required to represent the internal surface roughness of plastic pipes used in irrigation. In 2013, the roughness parameter Ra, traditional for the representation of surface irregularities in most situations, and the parameters Rc, Rq, and Ry were estimated based on 350 samples of polyvinyl chloride (PVC) and low-density polyethylene (LDPE) pipes. Pressure losses were determined from experiments carried out in laboratory. Estimations of pressure loss varied significantly according to the roughness parameters (Ra, Rc, Rq, and Ry) and the corresponding pipe diameter. Therefore, specific values of roughness for each pipe diameter improves accuracy in pressure losses estimation. The average values of internal surface roughness were 3.334 and 8.116 μm for PVC and LDPE pipes, respectively.

Venturi injectors are commonly employed for fertigation purposes in agriculture, in which they draw fertilizer from a tank into the irrigation pipeline. The knowledge of the amount of liquid injected by this device is used to ensure an adequate fertigation operation and management. The objectives of this research were (1) to carry out functional tests of Venturi injectors following requirements stated by ISO 15873; and (2) to model the injection rate using dimensional analysis by the Buckingham Pi theorem. Four models of Venturi injectors were submitted to functional tests using clean water as motive and injected fluid. A general model for predicting injection flow rate was proposed and validated. In this model, the injection flow rate depends on the fluid properties, operating hydraulic conditions and geometrical characteristics of the Venturi injector. Another model for estimating motive flow rate as a function of inlet pressure and differential pressure was adjusted and validated for each size of Venturi injector. Finally, an example of an application was presented. The Venturi injector size was selected to fulfill the requirements of the application and the operating conditions were estimated using the proposed models.

Design of lateral lines consisting of microtubes enables to optimize water distribution uniformity. In addition, there must exist a range of pressures at the lateral line inlet in which the water distribution uniformity remains acceptable. Thus, such emitters are interesting for use in micro-irrigation systems supplied by alternative power sources, in which temporal variability in the electrical power supplied to the pumping systems normally occurs. This study presents a methodology for designing lateral lines with microtubes operated under varying pressure, using the step-by-step method in order to establish the recommended range of lateral line inlet pressures. The proposed methodology was validated over three replicates by testing maximum, minimum and optimum pressures. Deviation between estimated and observed values of flow rate was lower than 6%, indicating a satisfactory accuracy. Distribution uniformity of the system was higher than 95% under all pressures within the estimated range of values. Lateral lines can operate within a wide range of operating pressures and even so satisfactory results of distribution uniformity are obtained.

EFEITOS DA IRRIGAÇÃO DE NOGUEIRA-PECÃ NO RIO GRANDE DO SUL EZEQUIEL SARETTA Professor da Universidade Federal de Santa Maria, Campus Cachoeira do Sul (Rodovia Taufik Germano, 3013, CEP 96503-205, Cachoeira do Sul, Rio Grande do Sul, Brasil). E-mail: ezequiel.saretta@ufsm.br. 1 RESUMO O cultivo de nogueira-pecã tem aumentado no Brasil, contudo pouco se conhece sobre a irrigação para essa cultura. Em climas semiáridos, a suplementação de água é obrigatória, e em climas úmidos, pesquisas indicaram resultados promissores na produção, porém com variedades e condições ambientais distintas daquelas presentes no Brasil. Por isso, este trabalho teve por objetivo avaliar os efeitos da irrigação na nogueira-pecã, em experimento conduzido em pomar com a variedade ‘Barton’ em Cachoeira do Sul, RS, entre as safras 2019-2020 e 2020-2021. Aplicaram-se doses de reposição da evapotranspiração da cultura (ETc) correspondentes a 0 (tratamento controle), 50, 100 e 150%, com microaspersão em blocos aleatorizados com três repetições. Avaliaram-se a circunferência do tronco, o tamanho, a quantidade e o peso de nozes e o peso e rendimento de amêndoas. Na primeira safra houve excedente de chuva na época de floração, e a irrigação não apresentou efeitos significativos. Por outro lado, na safra 2020-2021 houve incremento de circunferência do tronco das plantas irrigadas. Mesmo com maior quantidade de chuva no enchimento da amêndoa, a irrigação proporcionou maior tamanho e massa das nozes, com relação linear, indicando que as doses podem ser aumentadas para se obter a resposta máxima. Palavras-chave: Carya illinoinenses, microaspersão, irrigação localizada. SARETTA, E. IRRIGATION EFFECTS ON PECAN NUTS TREE IN THE RIO GRANDE DO SUL 2 ABSTRACT Pecan cultivation has been increasing in Brazil; however, little is known about the irrigation of this crop. In semi-arid climates, water supplementation is mandatory, and in humid climates, research indicated promising results in the production; although, with varieties and environmental conditions different from those present in Brazil. Therefore, the objective of this work was to evaluate the irrigation effects on pecan nut tree at an experiment conducted in an orchard with ‘Barton’ variety in Cachoeira do Sul, RS, between 2019-2020 and 2020-2021 growing seasons. Replacement doses of crop evapotranspiration (ETc) corresponding to 0 (control treatment), 50, 100, and 150% of were applied via microsprinkler in randomized blocks with three replicates. The trunk circumference, nut size, weight and quantity, and weight and percentage of kernel were evaluated. In the first harvest, there was an excess of rain during the flowering stage and the irrigation did not show significant effects. However, in the 2020-2021 harvest, there was an increase in the trunk circumference of the irrigated trees. Even with more rainfall during the kernel-filling stage, the irrigation contributed to enhancing the size and weight of nuts in a linear relationship, indicating that the doses can be increased to achieve the maximum response. Keywords: Carya illinoinenses; microsprinkler; localized irrigation.

CONVERSION OF SOLAR PHOTOVOLTAIC ENERGY INTO HYDRAULIC ENERGY APPLIED TO IRRIGATION SYSTEMS USING A MANUAL SUN TRACKING VANESSA DE FÁTIMA GRAH PONCIANO¹; ISAAC DE MATOS PONCIANO²; DINARA GRASIELA ALVES³; EZEQUIEL SARETTA⁴ E RUBENS DUARTE COELHO^{5   1} Professora Doutora, Instituto Federal de Educação Ciência e Tecnologia Goiano, Av. Oeste, 350, Loteamento Parque União, 76200-000, Iporá, Goiás, Brasil, vanessa.grah@ifgoiano.edu.br. ² Professor Doutor, Faculdade de Iporá, Rua Serra Cana Brava, 512, Jd. Novo Horizonte II, 76200-000, Iporá, Goiás, Brasil, ponciano.i.m@gmail.com ³ Doutora, Departamento de Engenharia, Universidade Federal Rural do Rio de Janeiro, Rod. BR 465, km 7, 23890-000, Seropédica, Rio de Janeiro, dinara_alves@hotmail.com. ⁴ Professor Adjunto, Universidade Federal de Santa Maria, Rua Ernesto Barros, 1345, Santo Antônio, 96506-322, Cachoeira do Sul, Rio Grande do Sul, Brasil, ezequiel.saretta@ufsm.br. 5 Professor Titular, Departamento de Engenharia de Biossistemas, Escola Superior de Agricultura Luiz de Queiroz, Av. Pádua Dias, 11, 13418-900, Piracicaba, São Paulo, Brasil, rdcoelho@usp.br.      1 ABSTRACT   Brazil has an unexplored solar energy potential, and only 1.2% of the energy matrix come from photovoltaic energy. Besides, water pumping is an important form of development in rural areas (family farmers) mainly because of the distance from distribution centers. Therefore, this paper aims to evaluate the energy conversion in a water pumping system applied to irrigation, powered by photovoltaic energy, and compare with a static system with a single axis manual three-steps sun tracking system. Two arrays of panels were installed in the field at 22° 42’30” S; 47°38’00” W; 546 m above sea level. One photovoltaic module was static and the other a manual sun tracking device. Each module was connected to an individual water pump to simulate an irrigation system. The results showed that the pumping system with manual tracking device had better performance in the energy conversion from photovoltaic to hydraulic, with increments of 177 MJ m^-2, 50.87 more pumping hours, and 66,135 L. However, the conversion energy efficiency from solar energy to water pumping was 4.55% and 4.77% for tracking and static modules, respectively. The manual sun tracking systems used in the photovoltaic module feeding a pumping system to irrigation was a technical alternative to improve the performance of the photovoltaic system.   Keywords: renewable energy, water pumped, pumping time, global efficiency. GRAH PONCIANO, V. F.; PONCIANO, I. M.; ALVES, D. G.; SARETTA, E.; COELHO, R.D. CONVERSÃO DA ENERGIA SOLAR FOTOVOLTAICA EM ENERGIA HIDRÁULICA APLICADA A SISTEMAS DE IRRIGAÇÃO UTILIZANDO UM RASTREADOR SOLAR MANUAL       2 RESUMO   O Brasil tem um potencial solar energético pouco explorado, apenas 1,2% da matriz energética é proveniente da energia fotovoltaica. Aliado a isso, o bombeamento de água é uma importante forma de desenvolvimento nas áreas rurais (pequenos agricultores) principalmente, devido a distância desses locais aos centros de distribuição de energia elétrica. Este trabalho tem por objetivo avaliar a conversão da energia em um sistema de bombeamento de água aplicada a irrigação, movido por energia fotovoltaica, comparando um sistema estático com um sistema rastreador solar manual com três ângulos de ajuste de eixo único. Dois conjuntos de módulos foram instalados no campo na localização de 22° 42’30” S; 47°38’00” W; 546 m acima do nível do mar. Um módulo permaneceu estático e o outro módulo com um sistema de rastreador solar manual. Cada módulo foi conectado a uma motobomba individual, simulando um sistema de irrigação. Os resultados mostraram que o sistema de bombeamento com o rastreador manual teve melhor desempenho na conversão da energia solar para hidráulica, com um incremento de 177 MJ m^-2, 50,87 h a mais no tempo de bombeamento, e 66.135 L. Contudo, a eficiência da conversão da energia solar para o sistema de bombeamento foi de 4,55% e 4,77% para o módulo rastreador e estático, respectivamente. O sistema manual de rastreamento solar utilizado no módulo fotovoltaico, alimentando um sistema de bombeamento para irrigação, foi uma alternativa técnica capaz de melhorar a desempenho do sistema fotovoltaico.   Palavras-chave: energia renovável, água bombeada, tempo de bombeamento, eficiência global.